Due to increasing scarcity of fluid fossil fuels such as oil and natural gas, much attention is being directed towards converting solid carbonaceous materials such as coal, oil shale, and solid waste to liquid and gaseous hydrocarbons by pyrolyzing the solid carbonaceous material. Typically, pyrolysis occurs under nonoxidizing conditions in the presence of a particulate source of heat.
In the past, pyrolysis has been carried out in reactors with long pyrolysis time. The hydrocarbon product of reactors having a long pyrolysis time has been less than desired. This has been attributed to protracted effective pyrolysis times which result in thermal cracking of hydrocarbon product.
Use of tubular reactors providing a short pyrolysis time results in less thermal cracking. However a disadvantage of using a tubular reactor for pyrolysis is the caking or agglomeration problem. Experience with agglomerative coals, particularly Eastern United States coals, indicates that these coals pass through a "tacky" stage during which the coal particles have a tendency to agglomerate in some types of tubular reactors, especially along the walls of the reactor.
A need exists therefore for a more efficient pyrolysis process and a more efficient pyrolysis reactor which minimize pyrolysis time and which prevent coal from agglomerating along the walls of the reactor.